Particle classifier for refuse screenings and the like



C. E. RICH Dec. 10, 1957 PARTICLE CLASSIFIER FOR REFUSE SCREENINGS ANDTHE LIKE Filed April 16, 1956 INVENTOR. Ckf/Wd 22 1F 56%.

United rates PARTICLE CLASSIFIER FOR REFUSE SCREENINGS AND THE LIKEApplication April 16, 1956, Serial No. 578,482 4 Claims. (Cl. 209-138)My invention relates generally to separators or classifiers for use ingrain elevators, feed mills and the like, and more particularly todevices for classifying refuse screenlugs.

It is common practice in storage elevators and grain processing plantsto use dust collecting systems in connection with separators,classifiers and other equipment which is utilized to remove varyingquantities of foreign material from the grain. Much of this foreignmaterial comprises minute particles which are thrown into the atmosphereas dust, and which is normally removed by dust collecting systems andconveyed to a storage bin together with the larger particles of foreignmaterial such as, sand, pieces of leaf, tiny hairs or awns, skinparticles from theg rain, and the like. Inasmuch as the smaller dustparticles, when floating in the air in quantity, present a definiteexplosion or fire hazard, the same is removed by the dust collectingsystem at the several places where such dust is caused to be air-borne.Then, when a predetermined quantity of the refuse, screenings andcollected dust has accumulated in the storage bin or bins therefor, thesame is conveyed to a suitable vehicle for ultimate disposal. In thestorage bin, the collected airborne dust is deposited together with theheavier particles of refuse screenings. Heretofore, the handling of therefuse screenings during conveying of the same from the storage bin byconveyor belts, bucket elevators, and the like, has presented a definitefire or explosion hazard. it has been found that the smaller sized dustparticles are more liable to ignition and explosion that the largersized particles, and particles of a size sufliciently small to passthrough a 150 mesh screen are apt to explode in the presence of a spark.It has also been found that the percentage of particles sufiicientlysmall to pass through a 150 mesh screen varies between 14% and 36% of agiven quantity of refuse screenings. It has also been determined thatparticles larger than those above mentioned can be handled with relativesafety from fire or explosion due to sparks and the like. The primaryobject of my inventino, is therefore, the provision of novel means forseparating the finer particles from the refuse screenings so that thesame may be otherwise disposed of before such screenings are transportedto the point of ultimate disposal.

Another object of my invention is the provision of novel mechanism asset forth which may be easily and accurately adjusted for variousoperating conditions.

Still another object of my invention is the provision of classifyingmechanism of the type and for the purpose set forth which is relativelysimple and inexpensive to produce and install, which occupies a minimumof space, which is highly efficient in operation, and which is rugged inconstruction and durable in use.

The above and still further highly important bojects and advantages ofmy invention will become apparent from the following detailedspecification, appended claims and attached drawings.

Referring to the drawings which illustrate the invendischarge end of thescreen 11 is provided with a depend-/ 2,315,.h5ii Patented Dec. 16,

ice

tion, and in which like characters indicate like parts throughout theseveral views:

Fig. 1 is a view in side elevation of my novel classifier, some partsbeing broken away and some parts shown in section;

Fig. 2 is an enlarged transverse section taken substantially on the line22 of Fig. l; and

Fig. 3 is a fragmentary detail in section of one of the valves utilizedin my improved mechanism.

Referring with greater detail to the drawings, the numeral 1 indicatesin its entirety a housing structure comprising a lower generallyrectangular housing section 2 having opposed end walls 3, opposed sidewalls 4, an open top, and a closed bottom wall 5. The housing struc ture1 further includes an upper housing section or hood 6 comprising endwalls 7, opposed sidew alls 8 and a top wall 9, the upper section havingan open bottom. The lower marginal edge portions of the upper housingsection are upwardly spaced from the upper marginal edges of the lowerhousing section 2. A band 10 of airtight flexible material encompassesthe adjacent marginal edges of the lower housing section 2 and the hood6, and is secured thereto to provide a flexible substantially airtightjoint therebetween.

A flat horizontally disposed generally rectangular screen 11 is mountedin a rectangular frame 12 that is secured to opposite side portions andone edge portion of the flexible band 10 between the adjacent marginaledges of the upper and lower housing sections whereby to provide asubstantially airtight joint therebetween. The screen 11 cooperates withthe side and end walls of the upper and lower housing sections to definetherewith upper and lower chambers 13 nad 14 respecitvely. The screen 11is carried by a plurality of hanger bars or the like 15 that arepivotally secured at their lower ends to the opposite side of the screenframe 12 as indicated at 16. The upper ends of the hanger bars 15 arepivotally secured to bearing brackets or the like 17 rigidly secured toa means of support such as a frame or ceiling 18. The hanger bars 15prevent the weight of the screen 11 from being carried by the flexiblesealing band and permit limited reciprocatory movement of the screen 11longitudinally of the housing structure 1. Means for imparting suchreciprocatory movement to the screen 11 is conventional, and is shown ascomprising a motor 19, a crank element 20 on the drive shaft of themotor 19 and a pitman arm 21 pivotally connected one end to the crankelement 20 and at its other end to the adjacent end of the screen frame12.

Means for introducing material to be classified, such as refusescreenings, to the screen 11 comprises a chute 22 extending downwardlyfrom the storage bin therefor, not shown, and into a receiving hopper 23having suitable. valve means 24 therein for controlling delivery ofmaterial to the adjacent underlying end of the screen 11. Such a valvestructure is shown in Fig. 3 and is operative to introduce material tothe screen 11 while substantially sealing the adjacent end of the upperchamber against atmosphere. With reference to Fig. 1 it will be seenthat one end of the screen underlies the inlet hopper 23 and valve 24,and slopes slightly downwardly toward the opposite end of the housingstructure 1. A discharge chute or the like 25 is mounted on the oppositeend of the housing structure and extends downwardly from the adjacentend of the screen 11 to receive relatively heavy particles or tailingsfrom the screen 11 and conduct said tailings to a point of alternatedisposal, not shown. It will be noted that a second feeding valve 26identical to the feeding valve 24 is operative to cause discharge of thetailings through the discharge outlet 25 and seals the interior of theupper chamber 13 against atmosphere. The

ing flexible curtain 27 that engages the adjacent end wall 3 andportions of the discharge chute to prevent movement of air between theupper and lower chambers through the upper end of the discharge chute25.

The screen 11 is a woven mesh of smooth resilient threads of plasticmaterial preferably nylon, the threads of said screen being woventogether to define apertures sufficiently large to permit free passageof air therethrough. but of insuflicient size to permit passagetherethrough of any of the particles delivered to the screen 11 throughthe chute 22 and valve 24. Preferably the screen mesh is finer than aso-called 150 mesh screen so that few if any dust particles are capableof passing downwardly therethrough during feeding reciprocation of thescreen 11.

A conventional fan or blower is interposed in a conduit 29 one end ofwhich communicates with the lower chamber 14 as indicated at 30, and theother end of which communicates with a header 31 of an air filterindicated in its entirety at 32. The filter 32 is of a type in commonusage and is shown as comprising a housing 33 containing one or moretubular filter elements 34 the interiors of which communicate with theheader 31. A conduit 35 is connected at one end to one end of the hood 6and at its other end to the filter 32 adjacent the upper end thereof.Operation of the blower 28 causes air to be drawn from the header 31 andintroduced to the lower chamber 14 from whence it moves upwardly throughthe screen 11 and the chamber 13 of the hood 6, and from thence throughthe conduit 35 to the interior of the housing 33. The dust laden airpasses through the filter elements 34 which remove substantially all ofthe dust from the air, so that only filtered air is delivered to thelower chamber 14 by the blower 28. Dust removed by the filter 32 isdischarged therefrom through a suitable discharge outlet 36 having adelivery valve 37 therein, said delivery valve 37 being similar to thevalve 24 shown in Fig. 3.

A perforate equalizer plate 38 is mounted in the lower chamber 14 indownwardly spaced substantially parallel relationship to the screen 11and diffuses the filtered air entering the chamber 14 from the conduit29 so that upward movement of the filtered air through the screen 11 issubstantially equal over the entire area of the screen 11. For thepurpose of adjusting the volume and velocity of air moving upwardlythrough the screen 11, I provide a plurality of partition elements 39which converge downwardly to define upwardly tapering compartments 40which communicate with the upper portion 41 of the chamber 13 throughrestricted openings 42. With reference to Fig. 1 it will be seen thatthe conduit 35 communicates with the upper end portion 41 of the chamber13 above the restricted openings 42, and that the lower edges of thepartitions 39 are in upwardly spaced relation to the screen 11. Aplurality of dampers 43 are mounted one each in a different one of theopenings 42 and are operable to effectively enlarge or reduce the sizeof the several openings 42. The downward spacing of the screen 11 fromthe lower ends of the partitions 39 permits air passage upwardly throughthe screen 11 over the entire area thereof even when one or more of thedampers 43 is in a position to close its respective opening 42. Withreference to Fig. 1 it will be seen that a branch conduit 44 isconnected in communication with the conduit 29 between the blower 28 andthe chamber 14, and that a conventional damper valve 45 is mounted atthe junction between the conduit 29 and the branch conduit 44-. Thedamper valve 45 may be regulated to control the amount of filtered airintroduced to the lower chamber 14. With the damper valve 45 in theposition shown by dotted lines in Fig. 1, a portion of the filtered airwill be exhausted to atmosphere or delivered to any desirable point.

In operation, the motor 19 is energized to cause reciprocatory movementsto be imparted to the screen 11, the blower 27 is caused to operate, andmaterial to be classified is caused to be fed downwardly through thechute 22 and delivery valve 24 onto the adjacent end of the screen 11.As the material is carried by the screen 11 toward the discharge outletor chute25, it is violently agitated by reciprocatory movements of thescreen 11 and air blowing upwardly therethrough causes the finerparticles to be separated from the material and to become entrained andcarried through the conduit 35 to the filter 32. The violent agitationimparted to the material by the screen 11 causes the finer and lighterparticles to become dislodged from the coarser particles to which theymight adhere and to become more easily entrained. Inasmuch as many ofthese finer particles include elongated awns and skin particles havingtiny barbs and other projections thereon, it has been found that the useof a conventional cloth screen becomes quickly choked with suchneedle-shaped particles. Thus, after considerable experimentation it hasbeen found that a woven screen made from extruded resilient plasticthreads is highly successful in remaining free from being choked by thesmaller particles which contact the screen before being carried away bythe air stream. Plastic threads such as nylon are devoid of the usualprojecting fiber ends generally found in cotton threads and the like,and have a smooth outer surface to which the barbs or projections on thedust particles have difficulty in adhering. Furthermore, the resiliencyof the nylon threads permits a substantial amount of flexing thereof sothat particles caught between adjacent threads are quickly dislodged andbecome air-entrained.

My invention has been thoroughly tested and found to be completelysatisfactory for the accomplishment of the objectives set forth; andwhile I have shown and described a preferred embodiment of my novelclassifier, it will be understood that the same is capable ofmodification without departure from the spirit and scope of theinvention as defined in the claims.

What I claim is:

1. In a particle classifier for refuse screenings, a housing structurecomprising a lower housing section and a hood in overlying spacedrelation to said lower section and an airtight flexible bandencompassing the adjacent marginal edges of said lower section and hoodand providing a flexible substantially airtight joint therebetween, agenerally horizontally disposed fiat woven mesh screen of smoothresilient threads of plastic material within said housing structure,said screen cooperating with said lower housing section to define alower chamber and with said hood to define an upper chamber, themarginal edges of said screen being secured to said flexible band toprevent air from passing therebetween from one of said chambers to theother thereof, means at one end of said housing defining a screeningsinlet for materials to be classified overlying one end of said screenand a tailings outlet underlying the opposite end of said screen, meansfor imparting reciprocatory movements to said screen to agitate materialdelivered thereon and feed the same toward said tailings outlet, saidscreen defining apertures of suflicient size to permit free movement ofair therethrough but of insuflicient size to permit passage therethroughof the particles of said material, an air filter, means including ablower and a cooperating conduit communicating with said lower chamberand said filter for delivering filtered air to said lower chamber andupwardly through said screen with suflicient volume and pressure tocause separation of particles on said screen and entrainment and removalof the finger particles upwardly through said upper chamber, and adisposal conduit for guiding air and the entrained particles away fromsaid upper chamber.

2. The structure defined in claim 1 in further combination with aplurality of generally upstanding partitions mounted in said hood anddividing said upper chamber into a plurality of upwardly taperingcompartments, the lower edges of said partitions being upwardly spacedfrom said screen, and damper means defining the upper ends of saidcompartments and operative to vary the volume and velocity of airupwardly through said screen.

3. The structure defined in claim 1 in which said disposal conduit iscoupled to said filter for delivery of entrained particles thereto, thefiltered air from the upper chamber being delivered to said lowerchamber by said blower and cooperating conduit.

4. In a particle classifier for refuse screenings, at housing structure,a generally horizontally disposed flat woven mesh screen of smoothresilient threads of plastic material within said housing and dividingthe interior thereof into upper and lower chambers, means at one end ofsaid housing defining a screenings inlet for material to be classifiedoverlying one end of said screen and a tailings outlet underlying theopposite end of said screen, means mounting said screen forreciprocatory movements in a direction to feed material from said inlettoward said outlet, said screen defining apertures of suflicient size topermit free movement of air therethrough but of insuflicient size topermit passage therethrough of the particles of said material, means forimparting reciprocatory movement to said screen to agitate said materialand feed the same toward said tailings outlet, an air filter, conduitmeans con necting said upper chamber to said air filter, means in- 6 4eluding a blower and a cooperating conduit communicat-' ing with saidlower chamber and said filter for delivering filtered air through saidlower chamber and upwardly through said screen with suflicient volumeand pressure to cause separation of particles on said screen andentrainment and removal of the finer particles outwardly through saidconduit means to said filter, partition means in said upper chamberdividing said upper chamber into a plurality of compartments, saidscreen defining the bottoms of said compartments, and damper means foreach of said compartments operative to vary the volume and velocity ofair upwardly through said screen.

References Cited in the file of this patent UNITED STATES PATENTS2,132,961 Morgan Oct. 11, 1938 2,206,337 Steele July 2, 1940 2,586,223Harmon Feb. 19, 1952 FOREIGN PATENTS 428,495 Italy Dec. 19, 1947

